Bis(thienyl)isopyrazoles and process for preparing and method for using bis(thienyl)isopyrazoles

ABSTRACT

The invention demonstrates the synthesis of a new pyrazole-containing monomer by means of an easily implemented two-step process. This monomer can be electropolymerized to yield a stable n-doping polymer that may easily be electrochemically characterized. It is demonstrated that the electrochemical behavior of the polymer films produced is dependent upon the conditions applied during electrodeposition. Films deposited by cycling only at relatively positive potentials (0 to 2000 mV) show less intense n-doping responses than those films obtained by scanning the applied potential throughout a wider range (−2000 mV to 2000 mV).

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part application, claiming the benefit of,parent application Ser. No. 12/178,972 filed on Jul. 24, 2006 now U.S.Pat. No. 7,829,660, which is a continuation of parent application Ser.No. 11/645,257 filed Nov. 25, 2008 which is now U.S. Pat. No. 7,456,295,which is the parent of divisional patent application Ser. No. 12/178,947filed Jul. 24, 2008 which is not U.S. Pat. No. 7,608,179, whereby theentire disclosure of which is incorporated hereby reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention described herein may be manufactured and used by or forthe government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

FIELD OF THE INVENTION

The invention generally relates to processes for preparingbis(thienyl)isopyrazoles via condensation and to methods for usingbis(thienyl)isopyrazoles.

BACKGROUND OF THE INVENTION

Electroactive polymers can generally be switched between two or morestable oxidation states, giving rise to changes in properties includingconductivity, color, volume, and transmissivity. [G. Inzelt, M. Pineri,J. W. Schultze, and M. A. Vorotyntsev, Electrochim. Acta, 45, 2403(2000)]. Electroactive polymers which have been oxidized from a neutralstate are said to be p-doped, by analogy to semiconductor terminology.Likewise, polymers that have been reduced from a neutral state are saidto be n-doped. Owing to the inherent stability of carbocations,p-dopable materials are quite well known and have been thoroughlydocumented. [G. Inzelt, M. Pineri, J. W. Schultze, and M. A.Vorotyntsev, Electrochim. Acta, 45, 2403 (2000); J. Jagur-Grodzinski,Polym. Adv. Tech., 13, 615 (2002); and, J. W. Schultze and H. Karabulut,Electrochim. Acta, 50 1739 (2005)]. However, stable n-doped polymershave heretofore been unreported. [D. M. de Leeuw, M. M. J. Simenon, A.R. Brown, and R. E. F. Einerhand, Synth. Met., 87, 53 (1997); K.Wilbourn and R. W. Murray, Macromolecules, 21, 89 (1988); and, M.Quinto, S. A. Jenekhe, and A. J. Bard, Chem. Mater. 13, 2824 (2001)].Such n-doped polymers would be desirable for the same reasons thatp-doped polymers have been desired and prepared, as well as for use inapplications such as batteries and supercapacitors, for example. [A.Rudge, J. Davey, I. Raistrick, S. Gottesfeld, and J. P. Ferraris, J.Power Sources, 47, 89 (1994)]. The instability of n-doping conjugatedpolymers is most likely due to the highly reactive nature of carbanions.[D. M. de Leeuw, M. M. J. Simenon, A. R. Brown, and R. E. F. Einerhand,Synth. Met., 87, 53 (1997)].

One approach being explored to obtain stable n-doping polymers is thesynthesis of donor-acceptor materials. [A. Berlin, G. Zotti, S. Zecchin,G. Schiavon, B. Vercelli, and A. Zanelli, Chem. Mater., 16, 3667 (2004);D. J. Irvin, C. J. DuBois, and J. R. Reynolds, Chem. Comm. 2121 (1999);P. J. Skabara, I. M. Serebryakov, I. F. Perepichka, N. S. Sariciftci, H.Neugebauer, and A. Cravino, Macromolecules, 34, 2232 (2001); and, H-F.Lu, H. S. O. Chan, and S-C. Ng, Macromolecules, 36, 1543 (2003)]. In adonor-acceptor type of system, the polymer HOMO (highest occupiedmolecular orbital) is energetically similar to the relativelyhigh-energy HOMO of the donor material, while the polymer LUMO (lowestunoccupied molecular orbital) is energetically similar to the relativelylow-energy LUMO of the acceptor. This type of electronic architectureleads to a small HOMO-LUMO gap in the polymers and consequently to alow-lying polymer LUMO suitable for accepting charge.

The electron-poor functionality of the acceptor groups can be obtainedin at least two ways. In the most common approach, electron-withdrawingsubstituents such as nitro- or fluoro-groups for example, areincorporated pendant to the main chain of the polymer. [D. J. Irvin, C.J. DuBois, and J. R. Reynolds, Chem. Comm. 2121 (1999); and, P. J.Skabara, I. M. Serebryakov, I. F. Perepichka, N. S. Sariciftci, H.Neugebauer, and A. Cravino, Macromolecules, 34, 2232 (2001)]. While thismethod can yield electron-deficient monomer units and ultimatelyelectron-deficient polymers, it is likely that the substituents act ascharge traps, hindering electron mobility.

Electron mobility might be improved, without the aid of pendant groups,by incorporation of functional groups that are themselves intrinsicallyelectron-deficient such as the high nitrogen heterocycles. Typically, asthe number of imine-type nitrogens replacing carbon in a given aromaticring increases, so too does that ring's electron affinity. [G. Brocksand A. Tol, Synth. Met., 101, 516 (1999)]. Empirically, the higher theelectron affinity of the polymer, the more stable the polymer will be inthe n-doped state. [A. P. Kulkarni, C. J. Tonzola, A. Babel, and S. A.Jenekhe, Chem. Mater. 16, 4556, (2004)]. Incorporation of these highnitrogen heterocycles into conjugated polymers should result inn-dopable polymers with good electron mobility. Limited research intothis type of donor-acceptor polymer has been conducted by others. [A.Berlin, G. Zotti, S. Zecchin, G. Schiavon, B. Vercelli, and A. Zanelli,Chem. Mater., 16, 3667 (2004); and, H-F. Lu, H. S. O. Chan, and S-C. Ng,Macromolecules, 36, 1543 (2003)]. The present invention discloses a newstable n-doping donor-acceptor polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a-1 e are Voltammograms generated by repeated cycling of appliedpotential at 30 mV/s during electropolymerization of DTDMPy, accordingto embodiments of the invention.

FIGS. 2 a-2 e is a diagram of redox cycling of poly(DTDMPy) showingprominent p-doping responses and faint n-doping signals, according toembodiments of the invention.

FIGS. 3 a-3 e is a diagram of electrodeposition of poly(DTDMPy) at 30mV/s with an expanded potential scan range (2000 to −2000 mV) to includen-doping potentials, according to embodiments of the invention.

FIGS. 4 a-4 e is a diagram of redox cycling of poly(DTDMPy) filmproduced with an expanded potential scan, according to embodiments ofthe invention.

FIGS. 5 a-5 e are Voltammograms of poly(DTDMPy) films indicating thatoxidation with an onset of 1200 and reduction centered at 200 mV arecoupled, according to embodiments of the invention.

It is to be understood that the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not to be viewed as being restrictive of the invention, as claimed.Further advantages of this invention will be apparent after a review ofthe following detailed description of the disclosed embodiments, whichare illustrated schematically in the accompanying drawings and in theappended claims.

DETAILED DESCRIPTION OF THE INVENTION

A donor-acceptor polymer based on thiophene and isopyrazole has beenprepared for use in n-doping applications. Non-polymerizable monomerradical cations appear to be the predominant oxidation product,resulting in a need for extended cycling to produce adequate quantitiesof polymer for characterization. Cycling to reductive potentials duringoxidative polymerization was necessary to produce a polymer film capableof n-doping, likely resulting from a need to establish pathways forcation migration. The electrochemical behavior of the polymer filmsproduced is strongly dependent upon the conditions applied duringelectrodeposition. The neutral polymer undergoes oxidation to thep-doped form at ca. 2000 mV vs. Ag/Ag⁺ and reduces back to neutral atca. 0 mV. Conversion of the neutral polymer to its n-doped form involvesreductions at −700 and −1300 mV, with re-oxidation at −800 and −200 mVto return to the neutral form of the polymer.

As the electron-rich portion of the polymer we have chosen thiopheneunits, while we have chosen the isopyrazole ring as the electrondeficient portion. The isopyrazole group provides high electron affinityand ease of functionalization. [G. Brocks and A. Tol, Synth. Met., 101,516 (1999)].

EXPERIMENTAL

Dimethyl malonyl chloride, n-butyllithium (2.5 M in hexanes), zincchloride (1.0 M in diethyl ether), 2-bromothiophene, and palladium (II)chloride were purchased from Aldrich and used as received.Tetrakis-(triphenylphosphine)palladium (0), also commonly writtenPd(PPh₃)₄, was synthesized by reduction of PdCl₂ with hydrazine in thepresence of triphenylphosphine, also commonly written PPh₃.

All electrochemical experiments were performed in a nitrogen atmospheredrybox using a PARSTAT model 2237 potentiostat. Acetonitrile was driedby distillation from calcium hydride. Propylene carbonate was dried bydistillation from calcium oxide. Tetramethylammonium tetrafluoroborate(TMABF₄) was recrystallized twice from methanol/water. The electrolytewas then dried in a vacuum oven at 110° C. for twenty-four hours beforeuse. Electropolymerizations were conducted with a 10 mM solution ofmonomer in 100 mM TMABF₄/acetonitrile. The working, auxiliary, andreference electrodes were a platinum button (diameter=1.6 mm; area=0.02cm²), a platinum flag, and a non-aqueous Ag/Ag⁺ reference electrode,respectively. The potential of the Ag/Ag⁺ reference electrode wascalibrated using the ferrocene/ferrocinium couple. The reductionpotential of the couple was found to be 97 mV vs. the referenceelectrode. All potentials reported herein are relative to the Ag/Ag⁺reference electrode. Cycling of the polymer films was accomplished usingmonomer-free 100 mM TMABF₄ in propylene carbonate as the electrolytesystem.

Example 1 Synthesis of 1,3-Dithien-2-yl-2,2-dimethylpropane-1,3-dione(DNIDTPy)

2-bromothiophene (12.4 mL, 32.0 mmol) was added to 500 mL dry diethylether. Then n-butyl lithium (2.5 M in hexanes, 50.8 mL, 127.2 mmol) wasadded and the mixture was stirred for sixty minutes. After this time,ZnCl₂ (1.0 M in ether, 127.2 mL, 127.2 mmol) was added slowly, giving awhite precipitate. Next, the reaction mixture was allowed to slowly warmto room temperature and was then refluxed for four hours. Following thereflux period, the reaction mixture was cooled to room temperature andPd(PPh₃)₄ (1.85 g, 1.6 mmol) was added followed by the slow addition ofdimethyl malonyl chloride (2.0 mL, 15.1 mmol). After completion of theadditions, the reaction mixture was brought to reflux and stirredovernight.

After this time, the reaction mixture was poured into 500 mL saturatedaqueous sodium bicarbonate. The two-phase mixture was filtered andseparated. The organic phase was washed with brine and dried over sodiumsulfate. The solvent was removed by rotary evaporation to give a paleorange solid. This solid was dissolved in a minimal amount of acetoneand passed through a short plug of silica gel using hexanes as theeluent. Upon removal of the solvent, a pale yellow solid was obtained.This material was recrystallized from hexanes to give pale yellowneedles. Yield 3.7 g, 23%. Mp: 159-162° C. ¹H NMR (CDCl₃) δ 7.54 (m,4H), 6.99 (dd, 2H, J=5.0, 4.0 Hz), 1.69 (s, 6H). IR (KBr pellet, cm⁻¹):3114.4, 3099.0, 2994.1, 2932.5, 1663.3, 1636.2, 1512.9, 1461.1, 1408.0,1352.6, 1268.8, 1254.0, 1241.7, 1172.6, 1054.3, 965.5, 903.9, 852.1,825.0, 748.5, 726.3.

Example 2 Synthesis of 1,3-Dithien-2-yl-2,2-dimethylpropane-1,3-dione(DNIDTPy)

DMDTPy (1.25 g, 4.7 mmol) and anhydrous hydrazine (1.5 mL, 47 mmol) werecombined in 100 mL toluene. The resulting solution was then refluxed foreighteen hours. After this time, the solvent was removed by rotaryevaporation and the bright orange solid remaining was collected anddried in vacuo. Yield 1.21 g, 98%. MP: 153-156° C. ¹H NMR (CDCl₃) δ 7.65(dd, 2H, J=3.8, 1.0 Hz), 7.52 (dd, 2H, J=5.0, 1.0 Hz), 7.17 (dd, J=5.1,3.8 Hz), 1.70 (s, 6H). IR (KBr pellet, cm⁻¹): 3095.9, 2988.0, 2972.6,2929.4, 2861.5, 1538.2, 1492.0, 1455.0, 1430.3, 1226.7, 1057.1, 850.4,835.0, 720.8, 699.3.

Discussion of Examples and Results

Synthesis of the monomer 3,5-Dithien-2-yl-4,4-dimethylpyrazole (DTDMPy)was accomplished using a novel two-step process (Diagram 1). The firststep of the process entails coupling a thienylzinc reagent to dimethylmalonyl chloride using a palladium (0) catalyst. The poor ethersolubility of the thienylzinc reagent likely contributed heavily to thelow yields (23%) attained. The target was easily separated from sideproducts by chromatography and further purified by recrystallizationfrom hexanes. The thienylzinc reagent was more soluble in THF than inether, but the material isolated after the reaction in THF was a complexmixture that could not be readily separated. Infrared spectroscopy ofthe product showed a sharp, prominent absorbance at 1636 cm⁻¹,indicating that conjugated carbonyl groups were present; ¹H NMR of theproduct was consistent with the proposed structure.

The second step of the process, a ring-closing reaction with excesshydrazine to provide the pyrazole ring, was accomplished in nearlyquantitative yield. This result indicates that the ring-closing step ismuch more kinetically favorable than is the addition of a secondhydrazine to the dione. Infrared spectroscopy of this product showed notrace of the carbonyl vibration observed with the precursor, indicatingthat the conversion to pyrazole was complete. It will be understood byone skilled in the art that this general reaction scheme may be appliedto other ring systems besides thiophene to give a wide array ofdiarylpyrazole derivatives, including those that are moreelectron-deficient than DTDMPy. Furthermore, one skilled in the art willbe able to incorporate many derivatives beyond the 4,4 dimethylpyrazole.For example, the 4,4 diethylpyrazole could also be synthesized by oneskilled in the art.

Diagram 1. Synthesis of 3,5-dithien-2-yl-4,4-disubstituted pyrazole(DTDSPy).

This general reaction scheme has been successfully applied to produceother diarylpyrazole derivatives including those substituted at the4-position of the pyrazole ring with alkyl chains, alkoxy chains, nitroalkanes, halo, cyanoester, mono and/or di-amines, ester, amides,alcohols, suflonates, silyls, and perfluoro alkyl as shown in Diagrams2-4, as well as to produce diarylpyrazole derivatives havingfunctionalized thiophenes as shown in Diagram 5, where R1 may behydrogen; alkyl of from 1 to about 22 carbon atoms; alkoxy includingfrom 1 to about 22 carbon atoms; nitro; halogen; cyano ester, mono- &di-alkylamine of from 1 to about 22 carbon atoms; ester groups includingfrom 1 to about 22 carbon atoms; amide including from 1 to 22 carbonatoms; alcohol including from 1 to 22 carbon atoms; amino; sulphonategroups; silyl; and, perfluoro alky including from 1 to about 22 carbonatoms; R2 selected from the group including of: hydrogen; alkyl of from1 to about 22 carbon atoms; alkoxy including from 1 to about 22 carbonatoms; nitro; halogen; cyano ester, mono- & di-alkylamine of from 1 toabout 22 carbon atoms; ester groups including from 1 to about 22 carbonatoms; amide including from 1 to 22 carbon atoms; alcohol including from1 to 22 carbon atoms; amino; sulphonate groups; silyl; and, perfluoroalky including from 1 to about 22 carbon atoms; R3 selected from thegroup including of hydrogen; alkyl of from 1 to about 22 carbon atoms;alkoxy including from 1 to about 22 carbon atoms; nitro; halogen; cyanoester, mono- & di-alkylamine of from 1 to about 22 carbon atoms; estergroups including from 1 to about 22 carbon atoms; amide including from 1to 22 carbon atoms; alcohol including from 1 to 22 carbon atoms; amino;sulphonate groups; silyl; and, perfluoro alky including from 1 to about22 carbon atoms. Such substitutions provide a means to manipulate theelectronic and/or solubility properties of the monomer.

Diagram 2. Synthesis of 3,5-dithien-2-yl-4-,4 disubstituted pyrazole.

Diagram 3. Synthesis of 3,5-dithien-2-yl-4-methyl-4-oligoether-pyrazole.

Diagram 4. Synthesis of 3,5-dithien-2-yl-4,4-difluoropyrazole.

Diagram 5. Synthesis of thiophene substituted3,5-dithien-3′-organo-2-yl-4,4-disubstituted pyrazole.

A vital consideration in monomer design is the substitution pattern ofthe pyrazole ring. In order to produce a monomer suitable forelectroactive polymers, it is necessary to quaternize the carbon at the4-position of the pyrazole ring. An unsubstituted pyrazole in thissituation has as its major resonance form a protonated amine as part ofthe ring (Diagram 6). Such an electronic structure of course serves as aconjugation break. In order to exclude this resonance structure, thecarbon at the 4-position must be fully substituted. Dimethyl malonylchloride, a commercially available building block, was used with theexpectation that the methyl groups would provide the correct electronicstructure for a fully conjugated polymer. In addition, afterelectropolymerization, the methyl substituents do not impart muchsolubility to the polymer. Indeed, the polymer films disclosed hereinare insoluble in both acetonitrile and propylene carbonate. Thisproperty facilitates electrochemical characterization of the films.

Diagram 6. Resonance structures of a 3,5-substituted pyrazole showing aconjugation-breaking major resonance structure and a minor structuregiving complete conjugation; 4,4-dimethyl analog with a “locked”electronic structure.

Initial electropolymerizations of DTDMPy were accomplished by cyclingthe potential applied to a platinum button repeatedly between 0 and 2000mV versus Ag/Ag⁺ reference. All electrochemical potentials are withrespect to this reference. It was necessary to cycle the potential fortwo hours to produce a film thick enough for electrochemicalcharacterization. This extended cycle time is in contrast to thosereported for more electron-rich monomers, such as thiophene derivativesthat can be deposited in a relatively shorter time. [G. P. Evans, inAdvances in Electrochemical Science and Engineering, H. Gerischer and C.W. Tobias, Editors, p. 1, VCH Publishers, Inc., New York, 1990]. Withreference to FIGS. 1 a-1 e, voltammograms generated by repeated cyclingof applied potential at 30 mV/s during electropolymerization showmonomer oxidation onset at about 1200 mV and peak at about 1800 mVtogether with a slowly increasing current response centered at about1200 mV. This increasing current response may be attributed to polymeroxidation. Interestingly, there is no discernable correspondingreduction for the polymer. Instead, reductions at more positivepotentials are present which are most likely due to monomer reduction.This suggests that a large portion of the monomer is first oxidized andthen reduced without coupling to form polymer. Hence, the polymerreduction response is most probably obscured by the more intense monomerreduction current.

The limited coupling occurring upon monomer oxidation may be explainedby considering the effect of the pyrazole ring on the resonance forms ofthe monomer. As is the case with a monomer such as terthiophene,oxidation gives a radical cation. The radical may be located at the5-position of a terminal thiophene, thus leading ultimately to2,5-linked polythiophene (Diagram 7). However, if the radical migratesthrough the terthiophene monomer, it may be located on the 3- or4-position of one of the thiophene rings. This electronic arrangementleads to the often-undesirable irregularly linked polymer chains thatare not fully conjugated.

Diagram 7. Oxidation forms of terthiophene and DTDMPy. Oxidation ofterthiophene showing structures giving rise to (a) desirable2,5-linkages and (b) often-undesirable 3,5-linkages; oxidation of DTDMPyshowing structures leading to (c) polymer and (d) monomerre-neutralization.

By analogy, DTDMPy may be oxidized, giving a radical cation in which theradical is located upon the 5-position of the terminal thiophene. Thisconfiguration or form of course gives rise to the desired polymer. Onthe other hand, the radical may migrate to the 3-position of thepyrazole ring so that the positive charge resides upon the nitrogen atthe 1-position of the ring. In this case, the steric hindrance aroundthe radical center most likely prevents any coupling. As the appliedpotential becomes more negative, the stabilized radical cations are thenreduced without coupling. The more prevalent structure or configurationis the resonance form in which the radical is located at the 3-positionof the pyrazole ring and the positive charge is found on the nitrogen,given that the monomer redox couple is much more intense in thevoltammograms than are the current responses corresponding to thepolymer.

With reference to FIGS. 2 a-2 e, upon cycling of the polymer film inmonomer-free 100 mM TMABF₄/propylene carbonate, a redox couple with anonset of about 1500 mV and peak about 1800 mV is readily observed. Therather positive potentials required to oxidize this polymer are mostlikely a result of the electron-deficient pyrazole units in the polymerbackbone. In addition to the p-doping signals, less intense currentresponses can be observed at more negative potentials, indicating thatthe polymer is being n-doped. The relative difference in intensitybetween the p-doping and n-doping regions of the voltammograms arelikely a result of the electrodeposition process. As the appliedpotential is cycled between 0 and 2000 mV to deposit polymer, anionsnecessarily migrate into the growing polymer film upon oxidation and outof the film upon reneutralization. This process establishes channels foranions to maintain charge balance during post-deposition cycling.Because these anion channels are established during film growth, theprocess of p-doping proceeds quite well. During polymer reduction, it islikely that cations must be able to freely move into and out of thefilm. Since the film was not n-doped during deposition, channels forcation migration were not established. Further, because thetetrabutylammonium cations are so much larger than the tetrafluoroborateanions, the anion channels are inadequate for cation transport.

In order to determine the effects of a broader cycling window, a newfilm was deposited by cycling the applied potential between −2000 and2000 mV. With reference to FIGS. 3 a-3 e, as observed previously withelectrodeposition scans between 0 and 2000 mV, the oxidative region ofthe voltammograms show oxidations corresponding to the monomer at about1500 mV and corresponding to the polymer at roughly 1200 mV. Inaddition, there is a faint n-doping process that can be discerned atroughly −1200 mV. The voltammograms from this electropolymerizationsuggest that both anions and cations are moving into and out of the filmduring the deposition process.

Cycling of the polymer films in monomer-free electrolyte solution yieldsthe following results shown in FIGS. 4 a-4 e. First, during the initialcycles between 2.0 and −2.0 V, the material shows very littleelectroactivity at all. However, the voltammograms change significantlyover the course of 50 cycles before eventually stabilizing. Initially,the polymer oxidation onset at 1200 mV is not accompanied by a peak thatcould be attributed to reduction of the polymer to the neutral state.The polymer oxidation gradually becomes more prominent with extendedcycling, and a reductive current response centered at 200 mV graduallydevelops. At the same time, more prominent current responses atrelatively negative potentials gradually become more intense. Thenegative current responses at −700 and −1300 mV are attributable toreduction of the neutral polymer to the n-doped state, while positivecurrent responses at −800 and −200 mV are attributable to oxidation ofthe n-doped polymer to the neutral state. These n-doping processes aremuch more intense than those obtained from electropolymerization overthe 0 to 2000 mV narrow potential window (FIGS. 1 a-1 e). Ion channelswere established during deposition by cycling between the potentialsnecessary to both oxidize and reduce the polymer, allowing both anionsand cations to move freely within the polymer and between the polymerand the electrolyte solution.

The changes in the voltammograms during extended cycling is thought tobe a result of trapped counter ions present in the film. It is usuallynecessary therefore to first condition the polymer films with severalpotential scans in order to free trapped ions and permit ion migration.However, some ion trapping may occur even after extended cycling. Withreference to FIGS. 5 a-5 e, the reduction observed at about 200 mV iscoupled to the polymer oxidation shoulder. An initial potential scanfrom 800 to 2500 mV shows that the polymer film displays a shoulder onthe solvent degradation signal that corresponds to polymer oxidation.This response, however, is not present on successive scans, indicatingthat the polymer has been oxidized and remained in its oxidized statethroughout the experiment. Based upon the evidence that the two signalsseparated by about one volt are in fact coupled, it is inferred thation-trapping is occurring.

While the present invention has been described in connection with whatare currently considered to be the most practical and preferredembodiments, it is to be understood that the invention is not to belimited to the disclosed embodiments, but to the contrary, is intendedto cover various modifications, embodiments, and equivalent processesincluded within the spirit of the invention as may be suggested by theteachings herein, which are set forth in the appended claims, and whichscope is to be accorded the broadest interpretation so as to encompassall such modifications, embodiments, and equivalent processes.

1. A process for preparing thiophene substituted1,3-Dithien-2-yl-2,2-disubstituted propane-1,3-dione (DMDTPy)comprising:

wherein R1 is selected from the group consisting of: hydrogen; alkylfrom 1 to about 22 carbon atoms; alkoxy from 1 to about 22 carbon atoms;nitro; halogen; cyano ester; mono- & di-alkylamine from 1 to about 22carbon atoms; ester groups from 1 to about 22 carbon atoms; amide from 1to 22 carbon atoms; alcohol from 1 to 22 carbon atoms; amino; sulphonategroups; silyl; perfluoro alky from 1 to about 22 carbon atoms; whereinR2 is selected from the group consisting of: hydrogen; alkyl from 1 toabout 22 carbon atoms; alkoxy from 1 to about 22 carbon atoms; nitro;halogen; cyano ester; mono- & di-alkylamine from 1 to about 22 carbonatoms; ester groups from 1 to about 22 carbon atoms; amide from 1 to 22carbon atoms; alcohol from 1 to 22 carbon atoms; amino; sulphonategroups; silyl; perfluoro alky from 1 to about 22 carbon atoms; whereinR3 is selected from the group consisting of: hydrogen; alkyl from 1 toabout 22 carbon atoms; alkoxy from 1 to about 22 carbon atoms; nitro;halogen; cyano ester; mono- & di-alkylamine from 1 to about 22 carbonatoms; ester groups from 1 to about 22 carbon atoms; amide from 1 to 22carbon atoms; alcohol from 1 to 22 carbon atoms; amino; sulphonategroups; silyl; perfluoro alky including from 1 to about 22 carbon atoms;dissolving 3-substituted 2-bromothiophene in dry diethyl ether to form afirst composition; dissolving n-butyl lithium in hexanes to form asecond composition; combining said first composition and said secondcomposition to form a third composition; stirring said third compositionfor a predetermined time, allowing contact of reactants, to form afourth composition; dissolving ZnCl₂ in ether to form a fifthcomposition; adding said fifth composition to said fourth composition toform a sixth composition; warming said sixth composition to roomtemperature to form a seventh composition; refluxing said seventhcomposition for a predetermined time, allowing further contact ofreactants, to form an eighth composition; cooling said eighthcomposition to room temperature to form a ninth composition; addingtetrakis-(triphenylphosphine)palladium (0) to said ninth composition toform a tenth composition; adding disubstituted malonyl chloride to saidtenth composition to form an eleventh composition; refluxing saideleventh composition for a predetermined time with stirring, allowingfurther contact of reactants, to form an twelfth composition; mixingsaid twelfth composition with saturated aqueous sodium bicarbonate toform a two-phase mixture having an aqueous phase and a first organicphase; separating said first organic phase from said aqueous phase;washing said first organic phase with brine to form a two-phase mixturehaving a brine phase and a second organic phase; separating said secondorganic phase from said brine phase; drying said second organic phase;removing the solvent from said second organic phase to form a residuecontaining thiophene substituted 1,3-Dithien-2-yl-2,2-disubstitutedpropane-1,3-dione (DMDTPy); and extracting DMDTPy from said residue. 2.The process in claim 1 wherein R1 is alkyl from 1 to about 22 carbonatoms; R2 is alkyl from 1 to about 22 carbon atoms; R3 alkyl from 1 toabout 22 carbon atoms.
 3. The process in claim 1 wherein R1 is alkoxyfrom 1 to about 22 carbon atoms; R2 is alkoxy from 1 to about 22 carbonatoms; R3 alkoxy from 1 to about 22 carbon atoms.
 4. The process inclaim 1 wherein R1 is nitro, halo, or cyanoester from 1 to about 22carbon atoms; R2 is nitro halo, or cyanoester from 1 to about 22 carbonatoms; R3 is nitro halo, or cyanoester from 1 to about 22 carbon atoms.5. The process in claim 1 wherein R1 is mono or diamine, ester or amidefrom 1 to about 22 carbon atoms; R2 is mono or diamine, ester or amidefrom 1 to about 22 carbon atoms; R3 is mono or diamine, ester or amidefrom 1 to about 22 carbon atoms.
 6. The process in claim 1 wherein R1 isamino; R2 is amino; R3 is amino.
 7. The process in claim 1 wherein R1 isalkylsulfonate and perfluoro alkyl from 1 to about 22 carbon atoms; R2is alkylsulfonate and perfluoro alkyl from 1 to about 22 carbon atoms;R3 alkylsulfonate and perfluoro alkyl from 1 to about 22 carbon atoms.8. The process in claim 1 wherein R1 is hydrogen; R2 hydrogen; R3 ishydrogen.